Battery operated electroluminescent film identification device

ABSTRACT

Apparatus containing a d.c. power source, a timing circuit, and a transformer to excite an electroluminescent material for use in a film identification device to imprint patient identification data on X-ray film. To preserve battery life the timing circuit will allow only enough electrical energy to be imparted to the transformer as is necessary to excite the lamp. Both the electrical energy coupled through the transformer and the energy stored in the transformer will be applied to the lamp to excite it.

D United States Patent 1191 1111 3,882,357 Nieuweboer et al. May 6, 1975 BATTERY OPERATED 3,743,918 7 1973 Maitre 315 219 x ELECTROLUMINESCENT FILM IDENTIFICATION DEVICE [75] Inventors: Gerrit Nieuweboer, Claymont; Primary EmmmermNathan Kaufman Martin A. Apostolico, Wilmington, both of Del.

[73] Assignee: E. I. du Pont de Nemours & [57] ABSTRACT Company, Wilmington, Del.

[22] Filed: Feb. 27, 1974 Apparatus containing a dc. power source, a timing circuit, and a transformer to excite an electrolumi- [21] Appl' 446535 nescent material for use in a film identification device I to imprint patient identification data on X-ray film. To [52] US. Cl. 315/209 R; 315/219 preserve battery life the timing circuit will allow only [51] Int. Cl. H05b 41/36 e ough electrical energy to be imparted to the trans- [58] Field of Search 315/209 R, 219, 267, 284, former as is necessary to excite the lamp. Both the 315/276, 360, 362; 252/244 P electrical energy coupled through the transformer and the energy stored in the transformer will be applied to [56] References Cited the lamp to excite it.

UNITED STATES PATENTS 3,646,926 3/1972 Plume, Jr 315/209 X 5 Claims, 6 Drawing Figures L ll \N l V V FIG- PATENTEDHAY SL975 SHEET 10F 3 PATENIEDHAY 61975 SHEET 2 OF 3 Vc o CONTROL VOLTAGE REFo 2 oTRlGGER e THRESHOLDC COMPARATOR coma/non 7 DISCHARGE w L A I FLIP- FLOP f OUTPUT STAGE a OUTPUT l GROUND PATENIEnuAfsms 3,882,357

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PIN 3'0UTPUT 0 0 *l '2 *3 7 TIME 5 FIG-3C VOLTAGE APPEARING on ELECTROLUMINESENT PANEL BATTERY OPERATED ELECTROLUMINESCENT FILM IDENTIFICATION DEVICE BACKGROUND OF THE INVENTION 1. Field of the Invention This invention relates to a system for exciting an electroluminescent panel for exposing a photosensitive material. More particularly it relates to an X-ray system in which a charged transformer and timing network are used to excite an electroluminescent panel to imprint patient identification data on X-ray film.

Numerous ways have been developed to satisfy the need to reliably identify a particular X ray film with a name and other pertinent data of the patient through the full process of exposure, processing, storage, and study of the film. The advent of electroluminescent ma terials gave rise to the development of thin and flat lamps that could be inserted into an X-ray cassette with a data bearing card interposed between the lamp and the X-ray film. Once inserted the electroluminescent lamp or electroluminescent panel, as these devices are commonly referred to, is electrically excited to produce a brief light pulse which exposes the flim to the image of data recorded on the card.

To construct such a lamp, for use in a film identifcation devise it is desirable to use an electroluminescent material which is excitable by an a.c. voltage rather than a d.c. voltage. Materials excitable by an a.c. voltage generally have a higher output and a longer life than those excitable by a d.c. voltage. It is also desirable that the film identification device contain both the lamp and its exciting energy source to make it small and self contained with no cumbersom electrical cord connected to a remote a.c. source. To accomplish this the energy source may be a battery which has its output converted to a form of a.c. which is then stepped up and coupled to the lamp by a transformer. A problem results in finding a battery that will provide adequate power to excite the lamp during frequent daily use over periods of many months. One of the solutions is to make the energy source and its associated circuitry connecting it to the transformer more efficient by controlling the amount of energy reaching the transformer and lamp. It is desirable to impart to the transformer only as much energy as is necessary to excite the lamp and to utilize all of the energy. This requires the use of not only the energy coupled through the transformer but also the energy stored in the transformer.

2. Description of the Prior Art None of the film identification devices disclosed in the prior art have the desirable features described above. US. Pat. Nos. 2,694,785 to C. E. Williams, 3,452,196 to F. L. Gray and 2,813,229 to J. M. Sacks are examples of electroluminescent lamps which are excited by a.c. signals but do not teach being selfcontained and powered by a d.c. battery. In addition, they do not teach the use of both the energy coupled through the transformer and the energy released by the collapsing transformer fields to excite the electroluminescent panels to preserve battery life. US. Pat. Nos. 3,488,753 to F. F. Tone et al. and 3,683,182 to Farmer teach the use of electroluminescent lamps in X-ray identification devices but do not teach the use of an a.c. voltage to excite them, the use of a battery, the use of transformer coupling, the use of energy released from the transformer or the integrated power source and electroluminescent lamp combination.

SUMMARY The present invention relates to an apparatus for for electrically exciting an electroluminescent material. The apparatus comprises a d.c. storage means for providing a d.c. voltage to a first and a second timing means and a transformer. A means for electrically connecting the d.c. storage means to the first and second timing means and the transformer is also provided. The first timing means generates a first gate pulse. The second timing means is electrically responsive to the gate pulse, generates a series of pulses occurring during the duration of the gate pulse and responds to the termination of the gate pulse to terminate the series of pulses. The transformer is electrically responsive to each pulse of the series of pulses to develop a voltage and apply it to the electroluminescent material. After the termination of each pulse, the transformer expends the energy stored in the transformer and applies an oppositely polarized voltage to the electroluminescent material. In this way, substantially all electrical energy applied to the transformer is transferred to the electroluminescent panel and a reduced amount of energy from the d.c. storage means is required to excite the electroluminescent material.

BRIEF DESCRIPTION OF THE FIGURES FIG. 1 is a schematic diagram of an electronic circuit used to excite an electroluminescent panel.

FIG. 2 is a block diagram of a timer circuit used in the electronic circuit of FIG. 1.

FIG. 3 illustrates the exciting pulses and the resulting voltage wave form across the electroluminescent panel.

FIG. 4 is a pictorial top view of a film identification apparatus utilizing the electronic circuit of FIG. 1 and the timer circuit shown in FIG. 2.

DESCRIPTION OF THE PREFERRED EMBODIMENT The apparatus of the present invention is comprised of an electroluminescent lamp which is excited by a.c. electrical energy coupled to the lamp through a coupling transformer and is useful for exposing identification data on X-.ray film. Both the energy coupled through the transformer and the stored energy released from the transformer are used to excite the lamp. The energy transfer is accomplished by the circuit illustrated in FIG. 1. The circuit contains 4 basic components, timers 26, 27, transistor Q and transformer 24. In general the two timers cooperate to provide a limited number of positive pulses which control the conducting state of transistor Q When Q; is in the conducting state current flows in the primary of transformer 24 and induces a positive pulse to the electroluminescent lamp. When 0 is in the non-conducting state, current is cut off in transformer 24 which generates a negative pulse across the lamp, because of a counter EMF which opposes the change of current flow in the transformer primary. The limiting of the number of pulses is accomplished by timer 26 initiating a long gate pulse whose leading edge starts the generation of the positive pulses by timer 27 and terminates them with the trailing edge.

Referring now to the specific circuitry of FIG. 1, when switch 11 is closed, the d.c. output of battery 10 or a similar d.c. storage device is applied to point 28.

This initiates the generation of the gate pulse by timer 26 by causing a low voltage to appear at pin 2 of timer 26. This starts the timer and causes an output voltage V which is the desired gate pulse, to appear at pin 3. The duration of the gate pulse is controlled by the time constant of capacitor C (0.01 ,ufd) charging through resistor R (2 meg Ohms). The gate pulse is terminated when the voltage across C reaches 2/3 of the battery voltage and is applied to pin 6 which turns off the timer and shuts off output V C will discharge through pin 6. The cycle is then ended and does not start again unless switch 11 is reactivated, since timer 26 operates as a one shot multivibrator and generates only one gate pulse for each activation of switch 11. It is necessary that switch 11 be of a non-bounce variety, to prevent multiple activations of the circuit.

The timers 26 and 27 are Signetics SE 555V/NE 555V integrated circuits (FIG. 2) which are capable of producing accurately timed delays and pulses controlled by externally connected resistor-capacitor networks and have terminals for resetting and triggering. Any other comparable timer would also be suitable.

The output gate pulse V from timer 26 is applied to light emitting diode 15 to activate it and provide a visual indication that the system is operating. Diode 15 is kept in the off state through resistance R (750 Ohms) and R (27 k Ohms) and is activated by V The output gate pulse V is also applied to pin 4 of timer 27 to start the timer and create the first pulse. As timer 27 starts it places a positive voltage at pin 3' which is the beginning of the first positive pulse. (T in FIG. 3B). The pulse duration is controlled by the time constant of capacitor C, (0.01 ufd) charging through resistance R, (68 K Ohms) and R (0.56 meg Ohms). The pulse terminates when C charges up to two-thirds of the battery voltage and applies this voltage to pin 6' to turn off timer 27 and shut off the output of pin 3 (T in FIG. 38). After the first pulse is terminated, there will be a gap until the second pulse is initiated. The length of the gap will be determined by the time constant of C discharging through R and into pin 7 which is grounded when timer 27 is shut off. When C discharges sufficiently, the voltage at pin 2 (through pin 6) will go low and restart timer 27 again to initiate another pulse.

The series of pulses generated by timer 27 are used to switch a 2N 2102 transistor 0,, or any other switching means, between the conducting state which allows current to flow in the transformer primary and the nonconducting state which restricts the current flow. When transistor O is in the conducting stage at time T as the first pulse is started, current flows through the trans former primary which presents a high resistance to the flow of current and causes the full battery voltage to appear across the primary. The voltage appears in the transformer secondary and is applied across the electroluminescent panel. As the current flow continues while transistor O is in the conducting state, a point is reached at which the transformer is saturated, a steady state current is established, and the voltage across the primary, secondary and electroluminescent panel have all dropped to zero. This point is where the positive a.c. pulse is calculated to terminate, and transistor O is designed to switch off current flow. If current flow were allowed to continue after saturation, the only limiting factor would be the internal resistance of the primary which would allow about 125 m a to flow as opposed to about 22 m a which is the average current expended during the positive pulse cycle. This would be a great, waste of battery power. This is the problem presented with using an operator activated switch to apply power to a transformer. An operator will hold a switch down for a minimum of about one second which allows the transformer to go well beyond saturation and waste large amounts of battery power. By using a transistor switch activated by a pulse the current to the transformer is cut off at saturation, and the problem is prevented. Otherwise expressed the current flow through the transformer primary is never allowed to reach or establish a steady state condition.

When transistor O is switched to the non-conducting state at time T as the first pulse is terminated, a high impedence path is presented between the transformer primary and ground which interrupts the current flow. A counter EMF opposes the change in current flow occurring in the primary. This opposition results in a negative voltage pulse in the secondary of the transformer and across the electroluminescent panel. Since transistor Q does not conduct during this time, no battery energy is used in the excitation of the electroluminescent panel for this part of the cycle.

At time T selected so that the period between positive pulses (i.e., T T approximates the period of the negative pulse, timer 27 generates a second positive pulse V at pin 3 that switches transistor Q back to conducting. Current flow is re-established in the primary of the transformer, and a positive voltage appears in the transformer secondary and across the electroluminescent panel. As this voltage goes to zero, following saturation and establishment of a steady state current in the primary, timer 26 at T completes its cycle, and output V goes to zero thus terminating the gate pulse. This shuts off timer 27 and puts transistor Q into the nonconducting state which causes a second negative pulse to appear across the electroluminescent panel. The pulse is left to dissipate in the electroluminescent panel and transformer with a number of decaying oscillations generated due to the inherent capacitance of the panel which tends to form a ringing circuit with the secondary coil inductance.

It should be noted that different values could be selected for the components of the circuit to change the time constants and time intervals needed to conform to different types of electroluminescent panels or alternative requirements of the system.

The electroluminescent panel used is comprised of an electroluminescent phosphor coated on a flexible substrate between two electrically conducting layers. The uppermost conductive layer is transparent to allow the light generated by the excited electroluminescent phosphor to reach and expose the film. A protective transparent coating is usually applied over the conducting layer to provide the needed electrical insulation and mechanical protection of the surface. Such panels are well-known in the art and any electroluminescent panel that provides sufficient output to expose a photographic film in addition to mechanical properties of strength and durability for use in a Hospital environment can be used.

FIG. 4 shows a pictorial top view of one form of the apparatus of the present invention. The electronic circuit, battery, and coupling transformer are all placed inside handle 29. This handle is usually made of a selected insulating and impact resistant material. It is comprised of a front and a back section which can be separated by loosening and removing three small screws 33 to reveal the electronic elements mounted on a printed circuit board which is secured to one of the two sections, preferably the one bearing activating switch 11 and light emitting diode 25. Battery becomes accessible and can be replaced. The electroluminescent panel 25 protrudes from one edge of handle 29. In the usual operation of the apparatus a card on which identification data has been typed is placed over the electroluminescent panel by folding the card and inserting the panel in the fold so that edge 31 rests against the inside of the folded edge of the card. The panel and card are then introduced into a mating slot on the side of an X-ray film cassette with the identification indicia against the X-ray film. The handle remains outside the cassette. Switch 11 is depressed to expose the identification data on the film. Following exposure, the film identification apparatus is removed from the cassette, and the operator proceeds with the normal X-ray exposure of the patient.

The present invention has been described in detail with particular reference to a preferred embodiment, but it will be apparent to those skilled in the art that modifications and variations of this invention are possible within the teaching of this disclosure. All such modifications and variations within the scope of the appended claims are intended to be within the scope of the present invention.

We claim:

1. Apparatus for electrically exciting an electroluminescent material, comprising:

a dc. storage means for providing a d.c. voltage to a first and second timing means and a transformer,

a means for electrically connecting said d.c. storage means to said first and second timing means and said transformer,

said first timing means generating an electrical gate pulse,

said second timing means being electrically responsive to said gate pulse and generating a series of electrical pulses, said electrical pulses occurring during the duration of said gate pulse, said second timing means being further electrically responsive to termination of said gate pulse and terminating said series of pulses,

said transformer being electrically coupled to said second timing means and developing a voltage in response to each pulse of said series of pulses, said transformer being further electrically coupled to said electroluminescent material and applying said voltage to said electroluminescent material, said transformer, upon termination of each pulse, expending substantially all energy therein to said electroluminescent material as an oppositely polarized pulse.

2. The apparatus of claim 1 additionally comprising:

a switching means being electrically responsive to each pulse of said series of pulses to initiate a flow of current through said transformer, said switching means being electrically responsive to the termination of each said pulse to cut off said current at or before the saturation of said transformer.

3. The apparatus of claim 1, additionally comprising:

a switching means electrically responsive to the termination of each pulse of said series of pulses and presenting a high impedance path between said transformer and ground.

4. The apparatus of claim 1, in which said means for electronically connecting said circuit is a non'bounce switch electrically connecting said d.c. storage means to said first and second timing means and said transformer.

5. Apparatus for exposing a photosensitive material comprising:

a d.c. storage means for providing a d.c. voltage to a first and second timing means and a transformer,

a means for electrically connecting said d.c. storage means to said first and second timing means and said transformer said first timing means generating an electrical gate pulse,

said second timing means being electrically responsive to said gate pulse and generating a series of electrical pulses, said pulses occurring during the duration of said gate pulse, said second timing means being further electrically responsive to the termination of said gate pulse and terminating said series of pulses,

a transistor switch being electrically responsive to each said pulse of said series of pulses and initiating a current flow through said transformer for each said pulse, each said pulse being of a limited duration to saturate said transformer, said transistor switch being electrically responsive to the termination of each pulse and presenting a high impedance path between said transformer and ground an electroluminescent material said transformer being electrically coupled to said transistor switch and developing a voltage in response to current flow through said transistor switch, said transformer being further electrically coupled to said electroluminescent material and applying said voltage to said electroluminescent material, said transformer being responsive to the presence of said high impedance path to ground, to expend substantially all energy stored in said transformer to said electroluminescent material as an oppositely polarized voltage. 

1. Apparatus for electrically exciting an electroluminescent material, comprising: a d.c. storage means for providing a d.c. voltage to a first and second timing means and a transformer, a means for electrically connecting said d.c. storage means to said first and second timing means and said transformer, said first timing means generating an electrical gate pulse, said second timing means being electrically responsive to said gate pulse and generating a series of electrical pulses, said electrical pulses occurring during the duration of said gate pulse, said second timing means being further electrically responsive to termination of said gate pulse and terminating said series of pulses, said transformer being electrically coupled to said second timing means and developing a voltage in response to each pulse of said series of pulses, said transformer being further electrically coupled to said electroluminescent material and applying said voltage to said electroluminescent material, said transformer, upon termination of each pulse, expending substantially all energy therein to said electroluminescent material as an oppositely polarized pulse.
 2. The apparatus of claim 1 additionally comprising: a switching means being electrically responsive to each pulse of said series of pulses to initiate a flow of current through said transformer, said switching means being electrically responsive to the termination of each said pulse to cut off said current at or before the saturation of said transformer.
 3. The apparatus of claim 1, additionally comprising: a switching means electrically responsive to the termination of each pulse of said series of pulses and presenting a high impedance path between said transformer and ground.
 4. The apparatus of claim 1, in which said means for electronically connecting said circuit is a non-bounce switch electrically connecting said d.c. storage means to said first and second timing means and said transformer.
 5. Apparatus for exposing a photosensitive material comprising: a d.c. storage means for providing a d.c. voltage to a first and second timing means and a transformer, a means for electrically connecting said d.c. storage means to said first and second timing means and said transformer said first timing means generating an electrical gate pulse, said second timing means being electrically responsive to said gate pulse and generating a series of electrical pulses, said pulses occurring during the duration of said gate pulse, said second timing means being further electrically responsive to the termination of said gate pulse and terminating said series of pulses, a transistor switch being electrically responsive to each said pulse of said series of pulses and initiating a current flow through said transformer for each said pulse, each said pulse being of a limited duration to saturate said transformer, said transistor switch being electrically responsive to the termination of each pulse and presenting a high impedance path between said transformer and ground an electroluminescent material said transformer being electrically coupled to said transistor switch and deveLoping a voltage in response to current flow through said transistor switch, said transformer being further electrically coupled to said electroluminescent material and applying said voltage to said electroluminescent material, said transformer being responsive to the presence of said high impedance path to ground, to expend substantially all energy stored in said transformer to said electroluminescent material as an oppositely polarized voltage. 